Lighttpd

Wiki

defines if the ETag generation algorithm will use the inode value of the file.If you have multiple lighttpd servers serving static content then you should use

etag.use-inode = "disable"

So that the ETag value is consistent across the lighttpd clusters. Otherwise you will generate lesser number of 304 responsesDo make sure that the static content on all your clusters have the same mtime (modified-time)